No negotiations after email received from ISIS

The Boston-based online news service GlobalPost received an email from James Foley's captors a week ago threatening to kill the photojournalist, held captive 21 months, GlobalPost President and founder Philip Balboni said Wednesday.

Balboni said the White House was aware of the threat, but no negotiations took place.

Foley, a 40-year-old journalist from Rochester, New Hampshire, went missing in northern Syria while freelancing for Agence France-Presse and GlobalPost. The car he was riding in was stopped by four militants in a contested battle zone that both Sunni rebel fighters and government forces were trying to control. He had not been heard from since.

Balboni said he was still hopeful after receiving the email.

"But you can see the seething anger. It could have been a bluff and we had to believe it was a bluff," said Balboni. "You know when you kidnap someone and hold them for almost two years, you don't do it unless you believe there is value in those hostages."

Balboni said he did not get confirmation of the execution until the video was released late Tuesday.

Balboni said "stronger action" by the United States is now needed, but he would not specify what that action should be.

"It warrants a stronger response," he said. "I would leave that to people who know more than I as to what that should be."

He called Foley a "wonderful, warm, funny, gregarious person" and that everyone at GlobalPost is devastated by the execution.

While the White House, State Department and FBI were involved in trying to find Foley, Balboni said the search largely was carried on by GlobalPost and the Foley family.

"We carried the burden of this investigation very much alone for a very long time," he said.